The present invention relates generally to a laser-based data communication interconnect apparatus for effecting optical data transfer and, more particularly, to compact optical transceiver apparatus and methods having improved thermal distributing and electromagnetic interference shielding features.
Optical transceiver modules are known in the data transmission field for effecting bidirectional data transmission, whereby electrical signals are converted to optical signals and vice versa. In operation, a transmitter unit of the module functions to convert incoming electrical signals to corresponding optical signals. Conversely, incoming optical signals are converted by the module's receiving unit into corresponding electrical data signals. These modules are typically mounted on a circuit host card that is normally associated with a host computer, input/output device, switch, or other peripheral device.
In general, space saving concerns are important to end users desiring to use such modules in order to satisfy established or emerging standards as to a size or form factor. It will thus be appreciated that there is a commercial desire for relatively small and compact modules; especially those that are adapted to be integrated into a wide range of existing and evolving networking systems.
Not only are compactness concerns important for module design, but so are thermal management issues. This is because transceiver modules, in operation, tend to generate relatively significant amounts of heat. In fact, as data transfer rates increase, for example in the multi-gigabit range, so does the heat generated thereby owing to the higher amounts of power required. It will be appreciated, therefore, that the higher power needs and the desire for module compactness tend to increase the amount of excessive heat generated within a module having reduced space for its components.
Not only do the smaller confines of a reduced sized module impact negatively on overall thermal management issues in a general sense, but such compactness places some of the module's components that operate at relatively high temperatures even closer to components that must operate at cooler temperatures, for optimal performance reasons, thereby adversely affecting the performance of the latter. For instance, in order to maintain high performance reliability for a module's laser diode, it should be kept relatively cooler than its associated driver; the latter of which tends to operate at much higher temperature ranges. Accordingly, significant and opposing design constraints are imposed on the manufacture and reliable operation of such transceivers considering the countervailing demands for more powerful transceiver components and end user demands for module compactness satisfying industry standards.
Many known transceiver modules when mounted to an opening of a data system bulkhead tend to block the passage of cooling air therethrough. This blockage is, in part, necessitated by the desire of shielding against excessive electromagnetic interference emissions emanating from such opening. The blockage creates, however, a tendency for the interior space of the data system which houses the module to overheat, thereby lessening the effectiveness of a module's internal cooling approach. Such blockages additionally place heating burdens on the data system itself. This is especially troublesome to end users when they desire more powerful transceiver modules because existing data systems may not be able to effectively cool the additional heat being added thereto.
As a result, emphasis is being placed on the utilization of heat sinks and other means for managing heat issues arising from transceiver use. Known attempts at addressing the heating problems in transceivers of this type include those described in commonly-assigned U.S. Pat. No. 5,757,998; issued to R. Johnson et el. This patent describes an optical transceiver having a cover and several components of the module serving as heat sinks. Also, insofar as electromagnetic interference is concerned, known attempts at addressing the need for a low cost and reliable approach for the reduction of electromagnetic interference emissions when mounting a transceiver to a wall opening include those described in commonly-assigned U.S. Pat. No. 6,085,006; issued to D. Gaio et al. This patent describes an optical transceiver having an external electromagnetic interference shield that slides over a module end portion that encloses an optical fiber connection assembly. The shielded end portion is retained in an opening of an associated data system for allowing connectors to be connected thereto.
While the known approaches have been successful concerning controlling thermal and electromagnetic interference issues, there is, nevertheless, a continuing desire to improve upon the control of such issues effectively. For without improvements regarding effective thermal and electromagnetic interference emission control management; especially in a compact and cost-effective manner, the ability of such transceivers to maintain reliable optimal performance characteristics in a commercially viable manner will continue to be limited.